Method for making IC card having severable mini chip card

ABSTRACT

A method for producing a mini chip card out of a standard card having an embedded semiconductor chip uses a punching die with cutting edges defining the outer contour of the mini chip card. The punching die is adjusted relative to the standard card and with respect to contact surfaces of the embedded semiconductor chip so that the edges of the punching die are at a predetermined distance from the contact surfaces. The punching of the standard card is performed in this adjusted position so that the contact surfaces are in a reference position with respect to the outer contour of the mini chip card. The punching forms the mini chip card in the correct position in the standard card. The mini chip card may initially remain connected to the standard card by thin bars between the cards.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a divisional application of U.S. patentapplication Ser. No. 08/200,584, filed Feb. 22, 1994, now U.S. Pat. No.5,362,955, which application is a continuation application of U.S.patent application Ser. No. 07/665,023, filed Mar. 5, 1991, nowabandoned.

BACKGROUND OF THE INVENTION--FIELD OF THE INVENTION

The present invention relates to a method for producing so-called "minichip cards," which are also referred to in the expert world as "plug-inSIMs," starting out from a check card according to the internationalstandard, which is referred to in the expert world as an "IC card."

BACKGROUND OF THE INVENTION--DESCRIPTION OF THE PRIOR ART

The term "check cards" when used in the following will refer to cardshaving at least one semiconductor chip embedded therein. Such cards areknown in diverse embodiments; they are intended to communicate withterminal units, such as money dispensers, vending machines, cardtelephones, access control units and the like, whereby the circuitintegrated in the semiconductor chip is activated via electric contactslocated in the terminal unit. Since terminal units from differentmanufacturers should be compatible with cards from differentmanufacturers, both the outer dimensions of such a check card and thesize and position of the contact surfaces relative to the outer edges ofsuch a check card have been standardized. The outer dimensions of thecard are international standardized by the standard ISO 7810, and thesize and position of the contact surfaces of the semiconductor chip bythe standard ISO 7816/2.

When a check card is inserted into a terminal unit, stop means locatedin the device bring the outer edges of the card in a certain positioninto which the contacts on the unit side are in contact with the contactsurfaces of the card. The contacting is only successful if the positionof the contacts is within the tolerance window defined by the standard.

Such a card meeting the international standard ISO 7816/2 will bereferred to in the following as a "standard card."

The check cards are normally punched out of multicopy sheets or strips,the punching dies being aligned with markings which in turn have acertain predefined position relative to the contact surfaces. Afterwardsthe outer edges of the punched cards must be positioned relative to thecontact surfaces in such a way that the tolerance window defined by thestandard for the contact surfaces is within the actually existingcontact surfaces.

The precision of the punching dies used is coordinated with theavailable ranges of tolerance, so that it is not possible, for example,to repunch a standard card, once it is punched, using a reference edgeof this card. In such a case the necessarily occurring positioningerrors would overlap, in the most unfavorable case, and result in avalue outside the acceptable extent of tolerance. A need thereforeexists for an exact positioning of a multicopy sheet, strip orprepunched card starting out from the contact surfaces, or for detectionof the actual position of the contact surfaces relative to apredetermined tolerance window. This localization or positioning shouldbe performed by a device of simple and compact construction that worksreliably and is easy to operate.

SUMMARY OF THE INVENTION

This problem is solved by a test head which works on the principle ofgalvanically scanning the limits or outer edges of the tolerance windowsdefined by the standard. The current flow is measured between a contactpin disposed in the middle of the tolerance window, for example, andcontact pins disposed at the edge of the tolerance window defined by thestandard.

Under certain conditions it may suffice to measure only one contactsurface and to deduce the correct position of the other contact surfacesfrom the correct position of this contact surface. However, embodimentsare preferred in which a plurality of contact surfaces are measuredsimultaneously in order to rule out angle offset errors. In the contactsurface plan according to the standard ISO 7816/2 contacts C6 and C8 arepreferably measured.

The test head has the advantage of being simple and robust, inparticular compared with known optical localizing systems.

The test head can therefore be used particularly advantageously for thequality control of standard cards, i.e. for detecting the position ofthe contact surfaces of standard cards with respect to their agreementwith the tolerance window defined by the standard. However, the testhead can also be used for positioning cards or carriers having embeddedsemiconductor chips for processing, in particular punching. This problemarises particularly during the production of check cards that are verymuch smaller than the check cards whose outer dimensions meet thestandard ISO 7810.

Current rapid developments in the relevant field, in particular theminiaturization of the terminal units, make it necessary to use checkcards that are very much smaller than the standard cards customary up tonow. In particular for mobile telephones, the so-called "mini chip card"has become accepted which is substantially smaller than a check cardwith international standardization of its outer dimensions, but whosecontact surface plan meets that of the standard card.

In the current introductory phase of mini chip cards, the productionmeans, and especially the personalization means, for check cards havingembedded semiconductor chips are invariably oriented toward the standardformat of ISO 7810, so that the substantially smaller mini chip cardscannot be personalized by conventional means. The various terminal unitson the market furthermore require a stock keeping both of standard cardsand of mini chip cards.

To solve these problems it would be advantageous if one could start outwith a standard card and punch the mini chip card out of the standardcard as the last production step. However, this is difficult because themini chip card would have to be punched out using the outer edges of thestandard card as reference edges. The outer edges of standard cards arealready within a certain range of tolerance with respect to the positionof the contact surfaces, so that in the most unfavorable case thepunching tolerances would add up.

According to the invention, a carrier having an embedded semiconductorchip, or its contact surfaces, are therefore adjusted relative to apunching die using the above-described test head, i.e. the positioningdoes not start out from the outer edges. During the subsequent punchingoperation the outer edges of the standard card are punched andsimultaneously the outer edges of the mini chip card--the latter notcompletely, but in such a way that the mini chip card remains connectedwith the standard card by small, easily severable bars. The bars aredisposed so as to be seated at places on the outer edges of the minicard that will not be used as reference points for subsequentlycontacting the mini chip card. Two reference points on a longitudinaledge and one reference point on the shorter transverse edge arecustomarily selected for correctly positioning the standard card or themini chip card in the terminal unit for contacting by the contacts onthe unit side.

The semiconductor chip is loaded or personalized after punching usingconventional means and devices, i.e. during this time the mini chip cardis still connected with the standard card. If the end user does notrequire the standard card, but rather the mini chip card, this mini chipcard is pressed out or punched out of the standard card by using acircular die to punch out the bar areas. Since the bar areas are locatedoutside the reference points on the edges, it plays no part if the outeredges have a concave indentation, for example, after the bar area ispunched away.

The described method is suitable in particular for punching mini chipcards out of prepunched standard cards. As already described, thestandard cards cannot be positioned by stop means cooperating with theouter edges. One instead uses the test head to put the card in areference position with respect to the contact surfaces. The secondpunching operation then takes place relative to the actual position ofthe contact surfaces and not to the actual position of the outer edgesof the standard card, which may already be at the edge of apredetermined range of tolerance. The mini chip card need not be punchedfully out of the standard card, but can remain connected with thestandard card by two or more bars to be removed later. The card cantherefore be used as a standard card with accordingly greaterdimensions, or else the mini chip card can be separated from thestandard card if required. The pressing or punching of the mini chipcard out of the standard card is an irreversible process; the cardcannot be subsequently reunited with the standard card.

A chip card is already known wherein the semiconductor chip is disposedon a plug-in part with substantially smaller dimensions than thestandard card. However, the edge areas of the plug-in part and thecooperating edge areas of the standard card are designed so as to havelocking means, so that the plug-in part can alternatively be used aloneor connected with the standard card. This special profiling of theengaged edge areas necessitates a fully separate production of theplug-in part, on the one hand, and the standard card, on the other. Thisknown chip card (German patent no. 38 04 361) therefore fails to achievethe effect aimed at by the invention, namely to produce a mini chip cardstarting out from a standard card.

Another chip card is known wherein the area of the card in which thesemiconductor chip is located is separated from the remaining card areaby a predetermined breaking line. The predetermined breaking line isintended to prevent stresses from being transmitted to the semiconductorchip when the card is twisted or bent during use. There is nopossibility or intention of separating the area bearing thesemiconductor chip and using this area as a mini chip card with definitestandardized dimensions (German "offenlegungsschrift" no. 34 20 051).

The advantages of the invention over the above-mentioned prior art arein particular that the stock keeping in the sales organization can bereduced since the customer can alternatively be offered cards having theouter dimensions according to ISO 7510 or the mini chip cards. The minichip cards can also be separated from the standard cards in the salesorganization using extremely simple means. A further advantage is thatthe mini chip cards can be produced using conventional personalizationand inscription devices since their format is only reduced in a lastmethod step. All preceding processing steps, such as the inscription ofthe card and loading of the semiconductor chip with the user group orpersonal data, can take place using conventional means.

BRIEF DESCRIPTION OF THE DRAWING

In the following, embodiments of the invention shall be described by wayof example with reference to the enclosed drawing, in which:

FIG. 1 shows the contact plan of a standard card according to ISO7816/2;

FIGS. 2a to 2d show arrangements of contact pins of a test head fordetecting the position of the contact surfaces;

FIG. 3 shows a schematic cross section through a test head acting uponcontact surfaces C2 and C6;

FIGS. 4a and 4b show a cross section through a punching means and afront view of a card fixed in the punching means;

FIG. 5 shows a front view of a standard card having a prepunched minichip card;

FIG. 6 shows the detail referred to as A in FIG. 5, and

FIG. 7 shows a prepunched mini chip card with shaded bar areas.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows schematically and not true to scale the contact surfaceplan of a standard card with eight contacts disposed in two parallelrows. The contacts have the following functions: the operating voltageof customarily 5 volts is supplied via contact C1; contact C2 serves tofeed a reset signal; a timing signal is fed via C3; C4 is reserved forfuture uses and is generally not connected with the semiconductor chip;C5 is on voltage 0; the programming voltage can be supplied in an orderof magnitude of approx. 25 volts via C6; C7 is for data input and dataoutput; and C8 is reserved for future applications.

In FIG. 1, reference number 1 marks the nominal contact surface (1.7×2.0mm) according to the standard ISO 7816/2. Reference number 2 marks anexample of the actual size of the contact surfaces (2.2×2.6 mm). Apartfrom the minimum size of the contact surfaces, the standard defines thecontact surface banks with respect to their spacing from the outer edgesof the card, since these outer edges serve as reference edges for asubsequent positioning of the card in the terminal unit. To compensatepunching tolerances, the actual sizes of the contact surfaces aregreater than the nominal sizes. In the case shown in FIG. 1 all nominalsurfaces are disposed centrically relative to the actual surfaces, whichwould mean positioning tolerances of +-0. But in practice such a casewould hardly occur. In the case shown, positioning tolerances of +-0.3in the X direction and +-0.25 in the Y direction would be possible. Inthe borderline case, two edges of a nominal window would therefore becongruent with an actual contact surface. If a nominal area 1 protrudesbeyond an actual area 2, this is an impermissible case that must beconsidered a reject.

The contact surfaces provided according to the standard are not presentin every case; for example contact surfaces C4 and C8 intended forfuture uses are lacking in some embodiments. It is thereforeadvantageous to test in particular contacts C6 and C2, contact C6because the programming voltage of 25 volts is frequently derived fromthe operating voltage (contact C1) and contact C6 is therefore notconnected with the chip at all. When testing contact C6 there istherefore no danger of an undesirable current flow through the chip.

FIGS. 2a to d show various contact configurations that permit testing ofcontact surfaces.

The test head shown schematically in FIG. 3 has a plate 12 made of anelectrically insulating material in which springy contact pins 3 to 10are guided. When a contact surface bank according to ISO 7816/2 istested the contact pins can be disposed in such a way that contact pins3 to 7 act upon contact bank C6, and contact pins 8 to 10 upon contactbank C2 (FIG. 2a).

Plate 12 of the test head is affixed to a lifting part 13 with which theentire test head can be moved toward the contact bank to be tested orremoved therefrom. The spring mount of the contact pins that elasticallyprestresses them with force F is not shown, but the expert knows anumber of possibilities for designing such a mount. The actual measuringcircuit of the apparatus is not shown either; what is measured is thecurrent flowing between center contact 3 or 8 and edge contacts 5, 6, 7or 9 and 10. such measuring circuits are familiar to the expert and aretherefore not shown separately.

If test currents flow between contact pairs 3-4, 3-5, 3-6 and 3-7 aftercontacting has been performed, all four circuits are closed and theposition of contact C6 is correct.

In some cases it suffices to measure only contact C6, i.e. if the actualsizes of contact C6 are smaller than or equal to the actual size of allother contacts, if the contact center clearances still deviate onlyinsignificantly from the theoretical value, if the angular deviation ofthe contact plan axes from the theoretical axes is small and, finally,if the distance between contact pins 7 and 4 or 5 and 6 is greater thanthe tolerance window defined by the ISO standard by an amount such thatthe differences nevertheless occurring necessarily with respect to thecontact center clearances and the angular deviation of the contact planaxes are compensated thereby. These conditions are frequently ensured byproducing or etching all contacts in one operation.

It is safer, however, to additionally test the position of contact C2 bycontact pins 8-9 and 8-10. Furthermore, other combinations of contactpins up to four pins per contact are possible (cf. the configurationsshown in FIGS. 2b, 2c and 2d). By accordingly analyzing the test resultsone can test any contact layouts as to their agreement with thetolerance zones defined by the standard.

If only one, or a small number of, contact surfaces are to be tested ithas proven advantageous to use contact C6 for a test first, since thiscontact is no longer connected with the chip in new semiconductor chipssince the programming voltage of 25 volts is generated via the operatingvoltage of 5 volts (C1).

All the configurations shown in FIGS. 1 and 2 constitute an ideal casein which the contact surface is disposed exactly centrically above thepredetermined minimum contact surface plan. In reality this situationwill rarely occur. With the dimensions of the standardized contact bankand actually used contact surface size given in FIG. 1 for bank C5, onehas a positioning tolerance of +-0.3 mm in the X direction and +-0.25 mmin the Y direction.

The described test head is preferably used in a punching means forpunching mini chip cards.

A binding international standard for these mini chip cards does not yetexist at present, but the mini chip card whose contours are shown inFIG. 5 is dimensioned in accordance with the international standard ISO7816/2. This means that three reference points B on the outer edges ofthe card must be spaced a certain distance from the contact surfacebank. Therefore, the second punching of a prepunched standard card leadsto intolerable deviations if the prepunched card is positioned by stopmeans cooperating with its outer edges.

However, it is possible to position the standard card with the test headfirst in such a way that the contact surface plan matches the tolerancewindow of the ISO standard. For this purpose card 11 (FIG. 4b) ispositioned in a slide by stop means 14, 15 and 16. Slide 14 isdisplaceable in the X and Y directions, for example by motor operators,and is adjusted until the contact plan shown (in the ideal case) inFIGS. 1 and 2 results, i.e. until all associated pairs of contact pinsdisplay a current flow. In this position, slide 14 with the card clampedthereto is fixed, test head 19 is removed from the punching means and astamping punch 23 moves through slide 14 against card 11 and punches, incooperation with die-plate 22, the mini chip card out of the standardcard in the correct position. Mini chip card 24 can be removed in thedirection of arrow 25, whereupon stamping punch 23 moves back again andcard 11 can be removed from the apparatus (FIG. 4a).

It is not absolutely necessary to punch the mini chip card outcompletely; it is instead useful not to punch out bar areas 30, wherebythese areas should be designed in such a way that they can be easilybroken out or at least easily punched out. FIG. 6 shows a speciallydesigned bar area 30 in an enlarged view. The predetermined breakingpoint is perforated with a laser beam along a seam 32 so that it is easyto break the bar without any left-over bar areas falsifying the outercontour of the mini chip card.

However, the mini chip card can also be punched out as in FIG. 7 bypunching out shaded areas 30. A concave indentation of the outer edge ofthe mini chip card at the place where the bars used to be has no effecton the correct position of reference points B relative to the contactsurfaces.

Bar areas 30 connecting the mini chip card with the standard card can bepunched out or severed at any time, preferably when it becomes clearwhether the customer needs a standard card or a mini chip card. The minichip card can be loaded with the user group or personal data andinscribed and all other production operations performed before the minichip card is definitively separated from the standard card, using anymeans and devices developed for standard cards up to now.

I claim:
 1. A method for producing a mini chip card from a standardcard, said standard card having outer edges and having an embeddedsemiconductor chip with contact surfaces, said contact surfaces beinglocated in agreement with a tolerance window defined by a standard andwithin a certain tolerance from the outer edges of the standard card,said method employing a punching die with cutting edges defining anouter contour of the mini chip card when produced from the standardcard, said method comprising the steps of:adjusting a position of thepunching die relative to the standard card by positioning the die withrespect to the contact surfaces so that the cutting edges of thepunching die are at a predefined position with respect to the contactsurfaces; and performing a punching operation with the punching die inthe adjusted position to form the outer contour of the mini chip card,the contact surfaces being in a desired position with respect to theouter contour of the mini chip card formed by the punching operation sothat the mini chip card is produced from the standard card with adesired positional relationship with respect to the contact surfaces. 2.The method of claim 1, characterized in that the position of thepunching die is adjusted relative to the standard card by using a testhead, which has a defined relationship with respect to the punching die,said test head having contact pins with tips, said method furthercomprising the steps of:touching at least two points of at least one ofthe contact surfaces of the embedded semiconductor chip with contactpins of the test head, at least at one of the points being located in anedge area of the tolerance window; applying a test voltage to thecontact pins, in the course of which a current flow between the contactpins indicates that the tips of the contact pins are resting on the atleast one contact surface and that the test head is in a correctposition relative to the standard card, and thereafter adjusting therelative position of the punching die and performing the punchingoperation.
 3. The method of claim 1, wherein the step of performing apunching operation is further defined in that the mini chip card remainsconnected with the standard card by thin, easily removable bars.
 4. Themethod of claim 3 having a further step in which the bars are removed insuch a way that the outer contour of the mini chip card formerlyconnected to the removed bars is substantially concave.